Nonequilibrium Diffusional Phase Transformations in Alloys Induced by Migration of Grain Boundaries and Dislocations

2019 ◽  
Vol 61 (2) ◽  
pp. 214-224 ◽  
Author(s):  
I. K. Razumov ◽  
Yu. N. Gornostyrev ◽  
A. E. Ermakov
Keyword(s):  
Phase Transformations ◽  
Grain Boundaries

scholarly journals Internal melt figures in ice by rapid adiabatic compression

1994 ◽  
Vol 40 (134) ◽  
pp. 132-134
Author(s):  
R.E. Gagnon ◽  
C. Tulk ◽  
H. Kiefte
Keyword(s):  
Phase Transformations ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Adiabatic Compression ◽  
Air Bubbles ◽  
Water Ice ◽  
Deep Focus ◽  
And Behavior ◽  
First Time

AbstractSingle crystals and bicrystals of water ice have been adiabatically pressurized to produce, and clearly illustrate, two types of internal melt figures: (1) dendritic figures that grow from nucleation imperfections on the specimen’s surface, or from air bubbles at grain boundaries, into the ice as pressure is elevated; and (2) compression melt fractures, flat liquid-filled disks, that nucleate at imperfections in the crystal and grow with the application of pressure eventually to sprout dendritic fingers at the periphery. The transparency of the ice permitted visualization of the growth and behavior of the figures, and this could be an important tool in understanding the role of phase transformations in deep-focus earthquakes. Correlation between figure size and pressure is noted for the first time.

scholarly journals Bicrystallography and Beyond: Example of Group–Subgroup Phase Transformations

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 560
Author(s):  
Denis Gratias ◽  
Marianne Quiquandon
Keyword(s):  
Phase Transformations ◽  
Grain Boundaries ◽  
The Other ◽  
Permutation Groups ◽  
Global Symmetry ◽  
Simple Link

This paper presents the basic elementary tools for describing the global symmetry obtained by overlapping two or more crystal variants of the same structure, differently oriented and displaced one with respect to the other. It gives an explicit simple link between the concepts used in the symmetry studies on grain boundaries on one side and group–subgroup transformations on the other side. These questions are essentially of the same nature and boil down to the resolution of the same problem: identifying the permutation groups that are images of the corresponding applications. Examples are given from both domains, classical grain boundaries with coincidence lattices and group–subgroup phase transformations that illustrate the profound similarities between the two approaches.

Electron Microscopy Observations on the Role of Twinning in the Evolution of Microstructures

2002 ◽  
Vol 8 (4) ◽  
pp. 247-256 ◽  
Author(s):  
U. Dahmen ◽  
C.J.D. Hetherington ◽  
V. Radmilovic ◽  
E. Johnson ◽  
S.Q. Xiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Transformations ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Equilibrium Shape ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron ◽  
Multiple Twinning

Twinning plays an important role in phase transformations and can have significant effects on microstructural evolution. Different roles of twinning in the development of microstructures during precipitation and phase transformations are reviewed and illustrated with examples from investigations by high-resolution electron microscopy, including the effect of multiple twinning on the development of Ge precipitates in Al-Ge and Ag-Ge alloys, the twin dissociation of grain boundaries in Au, the formation of hexagonal Si at twin intersections and the effect of twin boundaries on the equilibrium shape of Pb inclusions in Al.

The Role of Grain Boundaries and other Defects on Phase Transformations Induced by Severe Plastic Deformation

2015 ◽  
Vol 5 ◽  
pp. 77-92 ◽  
Author(s):  
Xavier Sauvage ◽  
Yana Nasedkina
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Grain Boundaries ◽  
Mechanical Mixing ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
Underlying Mechanisms ◽  
Scientific Questions

During the past two decades, processing of ultrafine grained materials using severe plastic deformation techniques has attracted great interest in the scientific community. Although the up-scaling of processes and the lack of ductility of ultrafine grained alloys are still some important challenges, these techniques look promising because they produce bulk materials free of porosities. More recently, some strategies to combine precipitation hardening and ultrafine grained structures have been proposed. It has also been shown that nanoscaled composite materials could be successfully processed. This experimental work rose however some very fundamental scientific questions about the influence of severe plastic deformation on the precipitation mechanisms or on the formation of supersaturated solid solution through mechanical mixing. The driving force and the thermodynamics of these phase transformations are of course affected by the high amount of energy stored in severely deformed alloys, especially as interfacial energy. But grain boundaries, with the help of dislocations and point defects, also play an important role in the kinetics. In this paper, it is proposed to shortly review these phenomena and the underlying mechanisms with a special emphasis on the contribution of grain boundaries.

scholarly journals Structural phase transformations in metallic grain boundaries

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Timofey Frolov ◽  
David L. Olmsted ◽  
Mark Asta ◽  
Yuri Mishin
Keyword(s):  
Phase Transformations ◽  
Grain Boundaries ◽  
Structural Phase ◽  
Structural Phase Transformations
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